Magnetite immobilized metal nanoparticles in the treatment and removal of pollutants from wastewater: a review

Abstract The increase in population and industrial activities has resulted in harmful pollutants in our water sources that cause a concern for our future health and environmental well-being. These pollutants include pharmaceuticals, nitroarenes, synthetic dyes, oil and heavy metals that can be toxic, carcinogenic and lead to multiple organ failure. Conventional methods used to remove these toxins are of high cost, poor recyclability and low efficiency. Therefore, it is important to find suitable methods to purify industrial and household wastewater. Nanoparticles possess useful characteristics such as high surface-to-volume ratio, high optical absorption coefficient and tunable band edges for optimized catalytic capability. Magnetite NPs in specific have proven great efficiency in the removal and degradation of such pollutants as it is affordable, recyclable and easy to remove in the presence of an external magnetic field. Surface functionalization of these magnetic NPs is seen as an excellent bridge between homogeneous and heterogeneous catalysis. A metal catalyst immobilized on the surface of these magnetic nanoparticles (MNPs) affords customization and optimization of their properties for targeted applications. This study briefly discusses the synthesis of the magnetic core and different immobilization methods used to secure a metal catalyst onto its surface. This is followed by a detailed discussion where these metal catalysts immobilized on MNPs are used to improve its absorption and degradation capabilities in wastewater treatment.